Preparation, characterization and toxicological evaluation of tapioca starch/chitosan/anhydrous citric acid composite edible films and their application in cooked rice.

Abstract

Cooked rice, due to its high content of nutrients such as moisture and protein, is susceptible to contamination, resulting in a short shelf life. In this study, a tapioca starch/chitosan/citric acid composite film (T/CTS/CA) was prepared to extend the shelf life of rice. Experiments showed that when the mass ratio of tapioca starch to chitosan was 4:5, the gelatinization temperature was 90 °C, and the glycerol addition amount was 3.0%, the comprehensive score reached the highest of 80 points. The T/CTS/CA composite film exhibited excellent mechanical properties, barrier properties, and antibacterial activities. Structural characterization confirmed that it possessed a dense and stable network structure as well as good thermal stability. The safety evaluation of the T/CTS/CA composite membrane was carried out, and the results showed that the composite membrane was non-toxic and harmless, with no adverse effects on the blood, liver function, kidney function and major organs of mice. Finally, the composite film was applied to cooked rice. It was found that this fresh-keeping film significantly prolonged the freshness of cooked rice, inhibited the total colony count, and reduced the acid value, effectively extending the shelf life of rice by 4 days at 4 °C.